Currently, an expander and a compressor in an air conditioner are connected via a shaft, and the compressor is driven by means of power recovered from air expanded in the expander.
In the prior art, fluid machinery includes the expander and the compressor, wherein the expander is provided with an expander suction hole and an expander exhaust hole, and the compressor is provided with a compressor suction hole and a compressor exhaust hole. When a refrigeration circulating apparatus is started, the fluid machinery without a drive apparatus can be reliably self-started only under the pressure of a working fluid. When the fluid machinery is in a working state, the expander suction hole and the compressor suction hole are closed along with the rotation of the shaft. Specifically, during the closing period of the compressor suction hole, the expander suction hole is in an open state; and during the closing period of the expander suction hole, the compressor suction hole is in an open state and is not communicated with the compressor exhaust hole.
Since the expander suction hole is provided at a bottom of a lower bearing and a high-pressure fluid fed from the bottom exerts an upward impact force on a fan-shaped cam of a crankshaft, the axial movement of the crankshaft is increased, thereby making an expansion compressor operate unstably. An expander air suction control mode has a potential safety hazard of low reliability, with the accumulation of operating time, the abrasion of a cam in the air suction control mode is increased, a clearance between an upper end surface of the cam and a lower end surface of an expansion cylinder is enlarged, and seal failure is caused accordingly, thereby making it unable to perform air suction control. The structure of the expander is relatively complicated, and the expander is difficult to process.